June is upon us. The grueling Major League Baseball season grinds on. Mettle is being tested. Bonds have been forged. The hot summer looms.

In other words, things are starting to get difficult. It always is a challenge when you play 162 games after six weeks of Spring Training.

But for as many bruises and obstacles as there might be in the way of the 30 clubs of the big leagues, players, front-office people and fans all know that the ones who are still playing in October are the ones who can best deal with this adversity.

This week, it will get particularly tough for a few teams.

Take the Washington Nationals. They've been off to a slow start, but they've stayed afloat in the National League East in part because of two of the most exciting young players in baseball: outfielder Bryce Harper and pitcher Stephen Strasburg.

Well, this week, Harper will be on the disabled list with bursitis in his left knee and Strasburg will be trying to work his way back from a mild lat strain but could very well miss his next start. In the meantime, Washington, which enters Monday at 28-29 for the season, will need to regroup in a hurry, and the scheduled Tuesday return of outfielder Jayson Werth from the DL could help.

The Nats have a good chance to get going this week, with a Monday off-day followed by three-game home series against the Mets and Twins, but that doesn't make it any easier for Harper.

"I don't want to be sitting out right now," Harper said. "It's just one of those things where you've got to be smart about what you do and just try to come in every day and get better and do things the right way."

Out on the West Coast, the Dodgers are trying to get themselves out of the confusing, disappointing and injury-laden start to a 2013 season that began with huge expectations after expensive winter roster improvements.

Losing Matt Kemp hasn't helped. In fact, it's the latest right hook to the chin taken by the team and manager Don Mattingly, in addition to starter Hyun-Jin Ryu missing Sunday's start because of a foot bruise, Carl Crawford's balky hamstring, Josh Beckett's Monday appointment with a nerve specialist to try to determine why he's experiencing numbness in his fingers, and catcher A.J. Ellis also heading to the DL with an oblique strain.

Kemp, the NL MVP Award runner-up in 2011, just hasn't seemed right this year after offseason shoulder surgery, and he now finds himself on the 15-day DL with a hamstring strain.

One question racing around Dodger Stadium: Will the mercurial five-tool prospect Yasiel Puig be the answer to replace Kemp in center field and maybe stick in the lineup for good? We'll see starting Monday, with Puig having been called up from Double-A to make his big league debut.

Another question: Can the Dodgers snap out of this funk -- they lost to Colorado on Sunday to fall to 23-32, last place in the NL West and 11 games out of first -- and avoid what many expect to be serious personnel changes if they don't?

This week, the Dodgers have a good chance to make a few things right at home. They start a 10-game stand in Chavez Ravine with three games against the Padres, beginning Monday, followed by a key four-game set against the Braves to round out the week and three more next week against another NL West rival, the D-backs. Hanley Ramirez might be closer to a return from his DL stint because of hamstring woes.

"We have to get some bodies here," Mattingly said after another tough loss on Saturday. "We're thin in the outfield already. We have to do something. It's kind of ridiculous the last couple of days, we have two outfielders missing, and it's not bruises for a couple days. You worry about these injuries long-term."

Elsewhere, other teams that were expected to contend have issues of their own. There are comings and goings all over both leagues. The transaction wires will be buzzing over the next seven days with familiar names moving this way and that.

For example, the Rays still have to get by without their ace, David Price, who's out with a strained left triceps.

The Tigers have been rolling along without outfielder and leadoff man Austin Jackson, but they'll be glad to see him starting his own rehab assignment this week as he comes back from a pulled left hamstring.

The Rockies have been playing winning baseball but will have to do without their closer, Rafael Betancourt, who just started a 15-day DL stint. But the Angels figure to be getting the services of their center fielder, Peter Bourjos, sooner than later, which could move Mike Trout back to left.

The Blue Jays just shelved starter Brandon Morrow for a while, but they plan on getting back outfielder Rajai Davis soon, and starter Josh Johnson will be back from the DL and starting against San Francisco on Tuesday night.

The D-backs might have lost starter Brandon McCarthy to shoulder inflammation, but they're in first place in the NL West and could get a bit stronger soon. Second baseman Aaron Hill (broken hand) could face live pitching on Saturday and closer J.J. Putz (elbow strain) could throw off a mound.

Other teams are wondering about their own players on the mend.

Will the Brewers welcome back Corey Hart this week? Maybe not, but he could start a rehab stint. Will Jake Westbrook take a step forward or a step back from right elbow inflammation this week when he begins rehab, hoping to rejoin the rotation for the amazing, high-flying St. Louis Cardinals?

Here's one we do know: Andy Pettitte will return to the mound for the Yankees on Monday. The veteran lefty hasn't pitched since straining a back muscle in a May 16 start against Seattle, but New York's rotation has treaded water in his absence.

"I felt pretty confident it would just be the two weeks and that I would feel good coming back," Pettitte said. "I'm feeling good, and I'm looking forward to getting back out there."

The same could be said about Texas second baseman Ian Kinsler, who will miss at least another two weeks with a stress reaction in his rib cage, but it will give the Rangers more of a look at their top prospect -- and MLB.com's No. 1 overall -- Jurickson Profar.

And speaking of prospects, in New York, the second part of the future of the Mets' rotation could arrive soon.

Righty Zack Wheeler, like phenom Matt Harvey, is all over the headlines in the Big Apple these days as a callup from Triple-A seems inevitable. The only question is when, although Mets manager Terry Collins wouldn't speculate.

"I've got enough on my plate right now," Collins said Sunday. "I can't keep track of everybody in the organization all the time. Certainly, I know how he pitched. We all keep saying, 'He's on the way, he's on the way, he's on the way,' but he'll pitch his way here. When that time is, I have no idea."